Geographic Variability in the Reproductive Hormones and Oocyte Maturation of Bonefish (Albula vulpes) in the Bahamas
Bonefish (Albula vulpes) are an extremely popular sport fish that are a vital component of the multimillion-dollar recreational flats fishery. Despite its economic importance for many countries, there is little information available about many aspects of their reproductive biology. Significant gaps include analysis of the hormones that influence oocyte development and the nutrient levels in oocytes that drive embryonic and early larval development and how these parameters vary among habitats. The goals of this study were to characterize and quantify the reproductive hormones, oocyte developmental stages, and nutrient composition of oocytes from fish at or near spawning sites across multiple Bahamian Islands including Abacos, Chub Cay, Bimini, and Acklins. Egg samples were collected via cannulation from female fish (n=52) captured from flats habitats located near well-known pre-spawning aggregation sites during the 2018-2019 and 2019-2020 spawning seasons. Blood samples (n=46) were taken for analysis of testosterone and 17β-estradiol levels. Oocyte histology and biochemical analyses were conducted to assess the development of oocytes and their overall nutrient content, with a focus on fatty acids and amino acids. Hormone and oocytes stage results were similar between all sample islands, characterized by consistently high levels of testosterone with increasing levels of 17β-estradiol as oocytes approached final maturation as well as a high proportion of Vtg. 3 oocytes. Many significant differences were identified between the levels of fatty acids detected in oocytes from each island. However, SFAs consistently made up the largest portion, mainly due to palmitic acid (16:0) and steric acid (18:0). Essential fatty acids DHA, ARA, and EPA, were consistently detected at the highest quantities within polyunsaturated fatty acids at all islands, however, ARA was the only one found to be significant. Combined with the knowledge that the nutrients available for oocyte development and larval growth are directly linked to maternal diet, the differences identified between sample islands in this study are likely due to variation in prey availability. Thesis findings could indicate a variation in egg quality and survival within the Bahamian Archipelago.